A novel optimized eco-friendly simple spectrofluorimetric method for the determination of total catechins in green tea extract: Application to commercial tablet.

Green tea extract (GTE) contains antioxidants that are present in green tea. The active constituents of green tea extract are catechins. This study demonstrates a spectrofluorimetric method for measuring GTE's catechin concentration based on its native fluorescence. To design a quick, sensitive, and ecological spectrofluorimetric approach, all features were investigated and adjusted. This method relies on determining the GTE ethanolic solution's native fluorescence at 312 nm after excitation at 227 nm. The calibration graph displayed a linear regression for values between 0.05 and 1.0 µg mL-1. The detection and quantification limits of the proposed technique were 0.008 and 0.026 µg mL-1, respectively. Two pure catechins present in GTE, (-)-epicatechin and (-)-epigallocatechin gallate, were examined by the proposed method. The analytical estimation of GTE in the pharmaceutical tablet was achieved effectively using this approach. An adequate degree of agreement was found when the findings were compared to those obtained by the comparative technique. Therefore, the novel strategy may be used in the GTE quality control study with minimal risks to people or the environment. The quantum yields of catechins were estimated. The validated technique was accepted by the International Council of Harmonization criteria.

Green highly sensitive spectrofluorimetric method for rapid determination of tafluprost in its pure form and ophthalmic formulation.

A green, simple and easy spectrofluorimetric method was studied for rapid estimation of tafluprost (TFL). The native fluorescence of TFL was measured at 292 nm after excitation at 220 nm. The results were linear in water over the concentration range 50-600 ng ml-1 with a correlation coefficient r = 0.9999 and intercept 1.1555. The limit of detection and limit of quantification were found to be 7.87 and 23.86 ng ml-1 , respectively. Neither different pH nor surfactants enhanced the fluorescence intensity. The high sensitivity of this spectrofluorimetric method makes it suitable for analysis of low concentrations of tafluprost in commercially available ophthalmic formulations. This procedure was validated according to International Council for Harmonisation Guidelines.

Spectrofluorometric determination of clonazepam in dosage forms: Application to content uniformity testing and human plasma.

The present paper describes a developed and validated simple, highly sensitive and cost-effective spectrofluorometric method for determination of clonazepam (CNP). The proposed method depends on forming a highly fluorescent product through the reduction of CNP with Zn/HCl. The produced fluorophore exhibits a strong fluorescence at λem 350 nm after excitation at λex 250 nm. The use of carboxymethylcellulose (CMC) greatly enhanced the fluorescence intensity of the produced fluorophore to the extent of about 100%. Calibration curve showed good linear regression (r2  > 0.9998) within test ranges of 20-400 ng ml-1 with a lower detection limit of 0.67 ng ml-1 and lower quantification limit of 2.22 ng ml-1 upon using CMC. The method was successfully applied to the analysis of CNP in its pharmaceutical formulations and the results were in agreement with those obtained using a reference method. Furthermore, the content uniformity testing of the tablets was also performed. The application of the proposed method was extended to determine CNP in spiked human plasma sample as a preliminary investigation and the results were satisfactory.